San Francisco can still win NFC West and regain some momentum for playoffs with victory this coming Sunday against the Cardinals

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SEATTLE, WA - DECEMBER 23: Richard Sherman #25 of the Seattle Seahawks reacts after he intercepted a pass in the second half against the San Francisco 49ers at Qwest Field on December 23, 2012 in Seattle, Washington. (Photo by Otto Greule Jr/Getty Images)

A week ago, the Niners were being labeled favorites to win the Super Bowl.

Now the 49ers are wondering what hit them in a 42-13 loss to the surging Seattle Seahawks Sunday night, the team’ worst loss since Jim Harbaugh became head coach.

“It was a punch in the face,” 49ers cornerback Carlos Rogers told the Sacramento Bee after the game. “But the thing about it is we still have a chance to win the division, and we’re in the playoffs. It’s a new season once the playoffs start.”

Rogers is correct, of course. The 10-4-1 Niners still can win the NFC West championship with a victory over the Arizona Cardinals at home this Sunday, and they’ve already clinched a spot in the playoffs.

But Sunday night’s mauling at the hands of a 10-5 Seahawks team that has scored 150 points over its past three games leaves some big question marks hanging over Harbaugh’s team.

First, defensive lineman Justin Smith, who missed Sunday’s game, may also miss the Arizona game. How soon will he be able to return? Clearly, the 49ers defense is much better when he’s in the lineup.

And second, will tight end Vernon Davis (concussion) and wide receiver Mario Manningham (knee), both injured in Seattle, be able to return soon?

And then, of course, there’s the injury to the 49ers’ mojo.

The one-sided loss to Seattle was a physical and mental whipping. How will the 49ers react to it? Will they shake it off and bounce back, or have the Seahawks damaged the confidence of a team that looked so strong in beating the Patriots the week before on national TV?

“We’ll wake up tomorrow, we’ll have a half-game lead on the division,” Harbaugh told Sports Illustrated, “and we’ll come back to take care of business next week. … It’s all how we handle it, how we respond.”

The Niners certainly didn’t respond well Sunday night to a Seahawks team that jumped on them early for two quick touchdowns, then returned a blocked field goal to put up a 21-0 lead early in the second quarter. The Seahawks running game dominated the San Francisco defense and Seattle defenders – particularly cornerback Richard Sherman and safety Kam Chancellor – made big-time plays and big-time hits that seemed to stun the Niners.

That, and the loud home crowd – the Seahawks’ vaunted 12th man – turned CenturyLink Field into a deafening arena in which 49ers quarterback Colin Kaepernick could hardly be heard by his teammates at the line of scrimmage and seemed to be out of his rhythm.

Now, the 49ers face a challenge. They face a must-win game, need to shake off Sunday night’s humiliating loss and regain some momentum for the playoffs. It’s now unlikely, too, that they’ll be able to secure a first-round playoff bye.

“We’ve had some adverse times and we had one tonight,” linebacker Patrick Willis told Kawakami. “And I know we’ll be stronger for it, and that’s all that matters.”